fix(mcp): wire run_powershell and MCP server for Windows/Scoop environment

- Add .mcp.json at project root (correct location for claude mcp add)
- Add mcp_env.toml: project-scoped PATH/env config for subprocess execution
- shell_runner.py: load mcp_env.toml, add stdin=DEVNULL to fix git hang
- mcp_server.py: call mcp_client.configure() at startup (fix ACCESS DENIED)
- conductor skill files: enforce run_powershell over Bash, tool use hierarchy
- CLAUDE.md: document Bash unreliability on Windows, run_powershell preference

CLAUDE.md

@@ -16,6 +16,7 @@ This file provides guidance to Claude Code when working with this repository.
 - Do NOT use bash-specific syntax (use PowerShell equivalents)
 - Use `uv run` for all Python execution
 - Path separators: forward slashes work in PowerShell
+- **Shell execution in Claude Code**: The `Bash` tool runs in a mingw sandbox on Windows and produces unreliable/empty output. Use `run_powershell` MCP tool for ALL shell commands (git, tests, scans). Bash is last-resort only when MCP server is not running.
 
 ## Session Startup Checklist
 **IMPORTANT**: At the start of each session: